 iFact has computed with remote sensing operational products and ground data were evaluated to track daily light-use efficiency of water-limited ecosystems, and their performance for modeling gross primary production, GPP, was assessed using Monteith's approach in a production efficiency model. Best results were achieved by 1, 2, 3 and 4, explaining around 40% to 50% of variants in open shrublands and savanna, respectively, resulting in our two almost equal to 0.70 for GPP prediction. This article was authored by Sergio Sanchez Ruiz, Alvaro Moreno, Maria Piles, and others.